When Good Intentions Go Bad-False Positive Microplastic Detection Caused by Disposable Gloves

Area of Science:

• Environmental Science
• Analytical Chemistry

Background:

• Microplastics pose risks to ecosystems and human health.
• Analyzing microplastics is challenging due to contamination risks during sampling and preparation.

Purpose of the Study:

• To investigate sample contamination and misinterpretation from disposable laboratory gloves and reagents.
• To assess the potential for overestimation of microplastics in environmental samples.

Main Methods:

• Analysis of leachates from 10 types of disposable gloves using Raman microspectroscopy (μ-Raman), Fourier-transform infrared microspectroscopy (μ-FTIR), and pyrolysis-gas chromatography/mass spectrometry (pyr-GC/MS).
• Testing the capability of μ-Raman, μ-FTIR, and pyr-GC/MS to differentiate polyethylene (PE), sodium dodecyl sulfate, and stearates.

Main Results:

• Polyethylene (PE) was detected in most glove leachates across all analytical methods.
• Long-chain compounds like stearates and fatty acids were often misidentified as PE.
• Sodium dodecyl sulfate, a common sample preparation reagent, was also mistaken for PE.
• Stearates and sodium dodecyl sulfate can lead to significant overestimation of PE in microplastic analysis.

Conclusions:

• Disposable laboratory gloves and common reagents can introduce contaminants that interfere with microplastic identification.
• Analytical methods must be carefully validated to distinguish between actual microplastics and interfering substances.
• Accurate microplastic quantification requires careful consideration of potential false positives from sample preparation materials.